It is the final day of campaigning in the regional assembly elections in Catalonia, a campaign that has become increasingly acrimonious and personal. The stakes could not be higher for Madrid, as Spanish unity is on the line because the election could trigger a referendum on independence. Rich but as financially troubled as the rest of Spain, seven and a half million Catalans, more than Denmark, account for a fifth of the Spanish economy, or about the same as Portugal. A recent convert to independence, Artur Mas and his CiU supported Prime Minister Mario Rajoy’s conservatives for years in exchange for concessions. The polls say he will win, ahead of the left-wing independentists. Combined their seats, along with smaller parties, should see a pro-independence two-thirds majority in the new assembly, opening the way to a referendum. Rajoy rejects claims Madrid is to blame for Catalonia’s woes, and Mas has claimed Rajoy is behind a smear campaign of accusations of Swiss bank accounts. Observers say it is the dirtiest election in 25 years. Many have expressed surprise at the speed with which feelings have swung towards Catalonia going it alone, while some say Mas has cashed in on discontent with a snap election to hide his administration’s economic failings during his three years in office.